Suitable for both freshwater and saltwater applications, AQUATOP's D1HT submersible Digital Aquarium Heaters are equipped with a highly visible digital temperature display, an easy to use temperature control button, and a separately attached temperature sensor, providing a stable temperature environment for your aquatic life. The submersible feature allows for flexible placement, and the D1HT Series is also equipped with memory. This easy to read submersible Aquarium Nano Digital Heater is 25W and includes a single digital readout to precisely control your aquarium fish tank temperature. It also saves energy compared to regular analog heaters.